Jamil Soni Neto
Modern life would be quite different without decent batteries. Can you imagine powering your laptop on something like a standard automobile battery? It simply doesn’t bear thinking about. Although we may make fun of battery engineers for claiming that three hours of real-world usage is the equivalent of being unplugged for an entire working day, they really have worked miracles. Unfortunately, even though they may want to think they can, even battery engineers can’t bypass the laws of physics.

The performance of the current generation of lithium ion batteries is about to hit a wall, and if we want batteries with higher energy densities, an entirely new system will have to be developed. Among the many possible candidates, lithium-air batteries look very promising. When lithium oxidizes, it releases a lot of energy—so much so that, like sodium, it catches on fire. Lithium is also very light and reasonably abundant, making it the perfect element.

Except it’s very hard to make a lithium-air battery that lasts. One of the big issues is unwanted side reactions. The battery contains the lithium, which we are going to repeatedly burn, an electrolyte for transporting charge between electrodes and electrode material. As we oxidize the lithium, a lot of energy is freed up, and not all of it gets extracted to do work. Instead, some of it goes into powering side reactions.